One aspect of the Janko Keyboard (described in U.S. Pat. No. 360,255 and others) which constitutes an improvement over the conventional 7-5 keyboard is that the Janko provides a set of three keys for each note. This key duplication allows the musician to position his/her hand more comfortably and ergonomically. Another advantage of the Janko's key duplication is that a two-key note sustain function is provided: The performer may strike and hold a key on one row, hold another key of the same set (i.e., of the same note) with another finger of the same hand, release the first finger, and thus change hand position without muting the note. The same action may be carried out on a conventional keyboard, but often not as comfortably, since the depth (along the Y or front-rear axis) of the front portion of a standard white key is less than the distance between two Janko keys of the same set.
On a standard Janko Keyboard, keys of the same set move together. As noted in the present applicant's copending application Ser. No. 08/040,209, (now U.S. Pat. No. 5,469,772) various advantages are realized when all keys of the keyboard move independently. However, this raises the following question: If all keys move independently, how does one engineer a key sensing/tone generating system which features the advantages of independent key movement, yet retains the note sustain function described above?
Barreto (in U.S. Pat. No. 3,468,209, text column 2, line 50 thru text column 3, line 2) briefly describes two methods by which an independent-key Janko Keyboard may trigger tones. Whether the sustain function is retained by either of these methods is unclear; but one may presume that it is. However, regardless of whether the sustain function is retained, Barreto's key position sensing methods are very limited. They do not provide for velocity sensing or polyphonic aftertouch, nor do they provide the user with the option of disabling the sustain function, if desired. One reason the user may wish to disable the sustain function would be to produce fast repetitions of the same note. Barreto also does not provide a means by which keys of one set may trigger different tones.
To provide a keyboard musical instrument with keys grouped into sets wherein the sets can perform both sustain, repetition, polyphonic aftertouch, and other functions requires a departure from the prior art.